Helium Definition and 389 Threads

Homework Statement The question was, you have a Helium ion with one electron in its ground state. Then a second electron is added to the n = 10 level. What effect does the second electron have the first electron that is nearest the nucleus? Is the energy increased or decreased? Homework...

I am planning to do a high altitude balloon launch and I was wondering if anyone on this forum could help me figure out a few things. The payload+the balloon+the parachute= weigh around 2 pounds. I am looking to get 3 pounds of free lift (each pound of free lift equals 300 feet per minute...

I just need some clarification on this. It is well known that a balloon filled with helium will rise since helium is less dense than air, but what if the balloon were to stay the same weight, but the elastic itself has become much stronger, thus we could concentrate the helium even more...

Hi, Here is an info I don't manage to obtain from anywhere so far ! What is the "best-estimate" of the Helium abundance (the He/H ratio) in the interstellar medium of galaxies in the nearby Universe and at high redshift? I know the primordial He abundance is Y = 0.24 but what is the...

Hi, I would like to model an alternate to Muonic helium, and I need some help. I got this idea from a professor of mine who mentioned it off hand in a lecture. The idea is the following: Model a helium nucleus with one electron, and one muon. This would have two fermions "orbiting"...

Homework Statement A helium atom had two electrons in the first shell (1s). Explain, withour detailed derivation, what the value of the total spin quantum number is. Homework Equations ? The Attempt at a Solution Since the 2 electrons are in the first (1s) shell they must have...

Some scientists have reported up to date success with such devices as tokamaks and Z-pinch devices by reporting neutron radiation that they registered inside such reactors.It gives them hope to build such a devices as ITER for following fusion researches. Meanwhile there have been overlooked...

Homework Statement The speed of sound in fresh water at 293k is 1482 m/s. At what temperature is the speed of sound in helium gas the same as that of fresh water at 293k? Helium is considered a monatomic ideal gas (y = 1.67 and atomic mass = 4.003u). A)442K B)377K C)525K D)313K E)633K...

If you released a balloon filled with helium, how high would it go if it never burst from the pressure change?

I have confused myself with this by reading a combination of Wikipedia, books and my QM notes and I'm afraid I need someone to untangle me please. Basically what I want to know is, what are the consequences of the Pauli exclusion principle for the ground state of the helium atom? Here's my...

Homework Statement In a fusion reaction, the nuclei of two atoms join to form a single atom of a different element. In such a reaction, a fraction of the rest energy of the original atoms is converted to kinetic energy of the reaction products. A fusion reaction that occurs in the Sun converts...

For the ortho state of Helium, the spin part of the wavefunction is symmetric. There are 3 possible symmetric wavefunctions we can construct from the 2 electrons' spins. (^^) (vv) [1/SQRT2] { (^v) + (v^) } I am confused as to why this last state gives a total spin of one? The...

Looking thru some notes one this, I came across something which I can't get my head around. The Hamiltonian of the system (Helium atom) is H = H_1 + H_2 + W, the energies (kinetic and electron-nucleus) of electron 1, electron 2 and the interaction between the electrons themselves. To find...

Not sure if I understand why the helium-filled balloon hovering in a closed train car, upon acceleration of the train, "will fly forward inside the train car till it hits the front, it won't touch the back of it at all." - quoted from klockan3 I believe the problem ignores wind effects. I...

"In the helium lamp an electron from the discharge impacts on a He atom, ionises it and at the same time excites it to a superposition of several states. For simplicity, let us consider only the states that are of practical importance and assume that the He+ ion immediately after the impact is...

I'm no physicist but find it fascinating... so as a joke/problem I am trying to work out if filling my car's body panels, trunk, backseat area with helium or hydrogen would improve 0-60 performance and why. Assuming that I have hydrogen tight air bladders and neglecting weight distribution from...

Homework Statement Helium is used to fill a balloon of diameter 44 cm at 22 degrees C and 0.9 atm. The mass of a helium atom is 4.0026 u, the conversion factor from u to kg is 1.66 x 10^-27 kg/u, the conversion factor from atm to Pa is 1.013 X 10^5 Pa/atm, the universal gas constant is...

Can we ionize the helium atom at once? ie the two electrons simultaneously and not one after another. If yes, what is the ionization energy in this case?

Ok so when they compress the gas and remove the heat until it liquefies then how do they further cool the liquid. I know they can evaporate a little more of the liquid helium to cool it a little bit more. And i couldn't find much on how a pomeranchuk cell works . Any input will be...

Why their tracks after collision has an angle 90 degree? Any detail derive?

If I know that liquid helium at 4.2 K (boiling point) occupies 0.01065 L, then how do I calculate the pressure exerted on the walls of its containers if the helium evaporates and warms up to 30 K?

I have had this question in the back of my mind for a while. Hydrogen has 1 proton and 1 electron, and the atom is electrically neutral. So that means that the electrical charge from the electron and the proton cancel each other out as they have equal/opposite charge. Then when you add another...

Homework Statement The first ionization energy of an atom is the minimum energy needed to remove one electron. For helium, this is 24.6 eV. The second ionization energy is the additional energy required to remove a second electron. a) Calculate the second ionization energy of helium...

i know the rules of increasing and decreasing atom sizes down and across the periodic table. however, i have met one strange thing when i was given data to plot a graph. the hydrogen atom radius was stated as 32 pm, but helium was 50 pm. when i searched the internet, i found few websites...

Say I want to send a helium balloon into the sky. For all intents and purposes this balloon is circular, with volume V. I will fill it with helium to the same pressure as the air outside it (I assume that this is important). The weight of the balloon and the payload is W. So, I assume I have...

Helium is seen to be "lighter" than air only when it is confined in a balloon or similar so as to be able to displace the heavier stuff around it. Released loose, the atoms seem to mix with the air around very swiftly. I mean about 50 metres in 2 or 3 seconds, and then it seems to hang about...

Homework Statement The numbers following are the results of a lab experiment to find the spectral lines of Helium in a gas discharge tube. The lines I got were roughly: 703nm, 660nm, 590nm, 500nm, 490nm, 470nm, 450nm. The question is, what possible electron transitions could the...

Homework Statement Substitute an electron in a neutral hydrogen atom with a muon. a) calculate the Bohr radius of the ground state for this myonic atom of atom. The answer must be right to at least 2 significant digits. b) Calculate the fraction of the myon that is located inside the proton...

Homework Statement The question states "What mass can the balloon lift at sea level where the density of air is 1.22 kg / m^3".. Extra information given are, use of ideal gas equation is needed, which is pV = nRT where p is pressure, V is volume, n is number of moles, R is constant...

The problem is number 5.10 in Griffths introduction to quantum mechanics, It goes as follows: Discuss (qualitatively) the energy level scheme for helium if (a) electrons were identical bosons, and (b) if electrons were distinguishable particles (but with same mass and charge). Pretend these...

A balloon contains 0.40 mol of helium at 300K. calculate 1/ The number of Helium atoms in the balloon 2/ The average kinetic energy of the helium atom in the balloon 3/ The total kinetic energy of the helium atoms in the balloon I am having a lot of difficulties to manage the ideal...

Dear Forum members, Situation: 3000 litre of water is pressurized with 1 bar helium gas in closed tank. question 1: My question is that, if i know the solubility of helium gas in water at 1 bar partial pressure of helium over water at temp of 25 deg is 0.00145 g/litre, Whether i can apply...

This is a really confusing issue .. even when asked my professor in thermodynamics he tried to derive many theromdynamic equations and could not come to a conclusion about it if we have two cylinder piston systems ,, they both have the exact same conditions except the kind of gas in each one...

Homework Statement Question 1 An alpha particle traveling at velocity u makes an oblique elastic collision with a helium atom moving with a velocity which is negligible compared to u. After the collision the alpha particle moves in the direction inclined at 30 degrees to its initial direction...

Homework Statement A helium meteorological balloon is made of a bag of impervious fabric that does not stretch, and when fully inflated forms a spherical shell of 1m diameter enclosing the He. At launch it is filled with He (at STP) to 15% capacity. The launch takes place in the Antarctic, in...

I know there is a connection with the thermal conductive properties of a material and the electrical conductive properties, so I'm curious as to the electrical conductivity of superfluid helium (below the lambda point).

In a batch of liquid helium (say < 8* K.) is there a mixture of both ortho and para-helium, or is it only ground state para-helium.? I was under the impression that ortho was a meta-stable state which cannot decay to ground state Para-helium by radiative emission, but by meta-stable we are...

Question from my homework. I'm not exactly sure what I am doing wrong, and it is bugging me. I hope this post is in the right forum. Imagine that 9.9 g of liquid helium, initially at 4.20 K, evaporate into an empty balloon that is kept at 1.00-atm pressure. What is the volume of the balloon at...

Homework Statement How many cubic meters of helium are required to lift a balloon with 400kg payload to a height of 8000m where the density of air is 0.460kg/m^3 and the density of helium is 0.180kg/m^3. Assume that the balloon maintains a constant volume. Homework Equations \rho = M/V...

Why is it safe to suck the helium out of a balloon, but it is dangerous to ingest alpha particles? I guess the main question is what is the difference between an alpha particle and a helium atom? Aren't they both written as \stackrel{4}{2}He?

Homework Statement How many 3L balloons can you fill from a 20L tank of helium at a pressure of 14.4atm. Homework Equations Boyle's Law: P_{1}V_{1}=P_{2}V_{2} The Attempt at a Solution \frac{14.4atm\times20L}{1atm}=V_{2} I then divided the answer to thank by 3 to get the amount...

Homework Statement I have having difficulty explaining the splitting of helium atom energy levels for three different cases: 1)Coulomb interaction is ignored 2)Coulomb interaction is present but exchange interaction is neglected 3)Coulomb and exchange interactions are present The Attempt...

I am trying to figure out how Helium Leak Detectors work. If a leak detector is pumping on an enclosure that is at a low pressure, the detector will detect helium leaking into the system instantly as far as my human senses can tell. The helium will propagate 4 meters in a time so small I can't...

Forgive what might strike you as an excessively elementary question, as well as irrelevant, but... Well, at least I guarantee that it is not any classroom project! Imagine a mass of pretty clean helium (yeah, *I* know, but this is an academic exercise! :smile: It gets worse; read on!)...

I have an under water application where I need the maximum amount of buoyancy with a limit to the volume i can use for a lifting device. My question is how much more Newtons would be exerted for helium instead of oxygen, or hydrogen instead of oxygen underwater? What is the percentage...

matter in The universe is thought to be made up of 75 percent hydrogen and helium is thought to make up 25 percent of helium; Dark matter is thought to make up 25 percent of the universe and 75 percent dark energy; that's an interesting coincidence. , and currently physicists are not certain...

what is the degrees of freedom of helium gas ? shouldn't helium gas be diatomic ? If so , it will be 5 . i have problems differentiating monoatomic and diatomic . Though its obvious that mono is one atom and diatomic is 2 atoms . Is it possible to know whether its mono or diatomic from...

Why do we need helium for star formation?

The Wikipedia article on the Helium Atom goes through the Thomas-Fermi approximation and shows that when you use a screening parameter Z you can optimize the energy of the atom according to the following formula: \langle H \rangle = [-2Z^2 + \frac{27}{4}Z]E_1 (E_1 is elsewhere defined as the...

"neutron collides elastically with a helium nucleus" Homework Statement A neutron collides elastically with a helium nucleus (at rest initially) whose mass is four times that of the neutron. The helium nucleus is observed to rebound at an angle θ'2 = 40° from the neutron's initial...